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# MCQs: Normal Probability

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Find the area under the standard normal curve between z=0 and z=3.

A. 0.4987
B. 0.9987
C. 0.4641
D. 0.0010

IQ test scores are normally distributed with a mean of 100 and a standard deviation of 15. An individual's IQ score is found to be 110. Find the z-score corresponding to this value.

A. -1.33
B. 1.33
C. -0.67
D. 0.67

The lengths of pregnancies of humans are normally distributed with a mean of 268 days and a standard deviation of 15 days. A baby is premature if it is born three weeks early. What percentage of babies are born prematurely?

A. 9.21%
B. 8.08%
C. 6.81%
D. 10.31%

The distribution of cholesterol levels in teenage boys is approximately normal with and (Source: U.S. National Center for Health Statistics). Levels above 200 warrant attention. Find the probability that a teenage boy has a cholesterol level greater than 225.

A 0.0718
B 0.0012
C 0.0336
D 0.0606

An airline knows from experience that the distribution of the number of suitcases that get lost each week on a certain route is approximately normal with ? = 15.5 and Ï? = 3.6. What is the probability that during a given week the airline will lose less than 20 suitcases?

A 0.4040
B 0.3944
C 0.1056
D 0.8944

Assume that blood pressure readings are normally distributed with and A blood pressure reading of 145 or more may require medical attention. What percentage of people have a blood pressure reading greater than 145?

A. 99.91%
B. 6.06%
C. 0.09%
D. 11.09%

Assume that the salaries of elementary school teachers in the United States are normally distributed with a mean of \$32,000 and a standard deviation of \$3000. If a teacher is selected at random, find the probability that he or she makes more than \$36,000.

A. 0.1056
B. 0.0918
C. 0.4040
D. 0.9082

IQ test scores are normally distributed with a mean of 100 and a standard deviation of 15. Find the x-score that corresponds to a z-score of -1.645.

A. 79.1
B. 91.0
C. 82.3
D. 75.3

For the standard normal curve, find the z-score that corresponds to the 90th percentile.

A. 0.28
B 1.52
C 1.28
D 2.81

Find the z-scores for which 90% of the distribution's area lies between -z and z.

A.(-0.99,0.99)
B.(-1.645,1.645)
C.(-2.33,2.33)
D.(-1.96,1,96)